Derivation and quantization of robust non-local characteristics for blind watermarking

ABSTRACT

An implementation of a technology is described herein for deriving robust non-local characteristics and quantizing such characteristics for blind watermarking of a digital good.

RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 10/987,231, entitled “Derivation and Quantizationof Robust Non-Local Characteristics for Blind Watermarking”, which is,in turn, a continuation of U.S. patent application Ser. No. 09/843,279,filed Apr. 24, 2001, entitled “Derivation and Quantization of RobustNon-Local Characteristics for Blind Watermarking”, the disclosures ofwhich are incorporated by reference herein.

TECHNICAL FIELD

This invention generally relates to a watermarking technology.

BACKGROUND

“Digital goods” is a generic label for electronically stored ortransmitted content. Examples of digital goods include images, audioclips, video, digital film, multimedia, software, and data. Digitalgoods may also be called a “digital signal,” “content signal,” “digitalbitstream,” “media signal,” “digital object,” “object,” and the like.

Digital goods are often distributed to consumers over private and publicnetworks—such as Intranets and the Internet. In addition, these goodsare distributed to consumers via fixed computer readable media, such asa compact disc (CD-ROM), digital versatile disc (DVD), soft magneticdiskette, or hard magnetic disk (e.g., a preloaded hard drive).

Unfortunately, it is relatively easy for a person to pirate the pristinedigital content of a digital good at the expense and harm of the contentowners—which includes the content author, publisher, developer,distributor, etc. The content-based industries (e.g., entertainment,music, film, etc.) that produce and distribute content are plagued bylost revenues due to digital piracy.

Modern digital pirates effectively rob content owners of their lawfulcompensation. Unless technology provides a mechanism to protect therights of content owners, the creative community and culture will beimpoverished.

Watermarking

Watermarking is one of the most promising techniques for protecting thecontent owner's rights of a digital good (i.e., digital good).Generally, watermarking is a process of altering the digital good suchthat its perceptual characteristics are preserved. More specifically, a“watermark” is a pattern of bits inserted into a digital good that maybe used to identify the content owners and/or the protected rights.

Watermarks are designed to be completely invisible or, more precisely,to be imperceptible to humans and statistical analysis tools. Ideally, awatermarked signal is perceptually identical to the original signal.

A watermark embedder (i.e., en-coder) embeds a watermark into a digitalgood. It typically uses a secret key to embed the watermark. A watermarkdetector (i.e., decoder) extracts the watermark from the watermarkeddigital good.

Blind Watermarking

To detect the watermark, some watermarking techniques require access tothe original unmarked digital good or to a pristine specimen of themarked digital good. Of course, these techniques are not desirable whenthe watermark detector is available publicly. If publicly available,then a malicious attacker may get access to the original unmarkeddigital good or to a pristine specimen of the marked digital good.Consequently, these types of techniques are not used for publicdetectors.

Alternatively, watermarking techniques are “blind.” This means that theydo not require access to the original unmarked digital good or to apristine specimen of the marked digital good. Of course, these “blind”watermarking techniques are desirable when the watermark detector ispublicly available.

Robustness

Before detection, a watermarked signal may undergo many possible changesby users and by the distribution environment. These changes may includeunintentional modifications, such as noise and distortions. Moreover,the marked signal is often the subject of malicious attacks particularlyaimed at disabling the detection of the watermark.

Ideally, a watermarking technique should embed detectible watermarksthat resist modifications and attacks as long as they result in signalsthat are of perceptually the same quality. A watermarking technique thatis resistant to modifications and attacks may be called “robust.”Aspects of such techniques are called “robust” if they encourage suchresistance.

Generally speaking, a watermarking system should be robust enough tohandle unintentional noise introduction into the signal (such noise mybe introduced by A/D and D/A conversions, compressions/decompressions,data corruption during transmission, etc.)

Furthermore, a watermarking system should be robust enough and stealthyenough to avoid purposeful and malicious detection, alternation, and/ordeletion of the watermark. Such an attack may use a “shotgun” approachwhere no specific watermark is known or detected (but is assumed toexist) or may use “sharp-shooter” approach where the specific watermarkis attacked.

This robustness problem has attracted considerable attention. Ingeneral, the existing robust watermark techniques fall into twocategories: spread-spectrum and quantization index modulation (QIM).

With the spread spectrum-type techniques, the watermark indexes themodification to the host data. The host data is the data of theoriginal, unmarked digital signal (i.e., host signal). With typicalspread-spectrum watermarking, each bit (e.g., 0s and 1s) of thewatermark is embedded into the signal by slightly changing (e.g., addinga pseudorandom sequence that consists of +Δ or +Δ) the signal.

With quantization index modulation (QIM), the watermark is embedded viaindexing the modified host data. The modified host data is the data ofthe marked digital signal (i.e., marked host signal). This is discussedin more detail below.

Those of ordinary skill in the art are familiar with conventionaltechniques and technology associated with watermarks, watermarkembedding, and watermark detecting. In addition, those of ordinary skillin the art are familiar with the typical problems associated with properwatermark detection after a marked signal has undergone changes (e.g.,unintentional noise and malicious attacks).

Desiderata of Watermarking Technology

Watermarking technology has several highly desirable goals (i.e.,desiderata) to facilitate protection of copyrights of contentpublishers. Below are listed several of such goals.

Perceptual Invisibility. The embedded information should not induceperceptual changes in the signal quality of the resulting watermarkedsignal. The test of perceptual invisibility is often called the “goldeneyes and ears” test.

Statistical Invisibility. The embedded information should bequantitatively imperceptive for any exhaustive, heuristic, orprobabilistic attempt to detect or remove the watermark. The complexityof successfully launching such attacks should be well beyond thecomputation power of publicly available computer systems. Herein,statistical invisibility is expressly included within perceptualinvisibility.

Tamperproofness. An attempt to remove the watermark should damage thevalue of the digital good well above the hearing threshold.

Cost. The system should be inexpensive to license and implement on bothprogrammable and application-specific platforms.

Non-disclosure of the Original. The watermarking and detection protocolsshould be such that the process of proving digital good contentcopyright both in-situ and in-court, does not involve usage of theoriginal recording.

Enforceability and Flexibility. The watermarking technique shouldprovide strong and undeniable copyright proof. Similarly, it shouldenable a spectrum of protection levels, which correspond to variabledigital good presentation and compression standards.

Resilience to Common Attacks. Public availability of powerful digitalgood editing tools imposes that the watermarking and detection processis resilient to attacks spawned from such consoles.

False Alarms & Misses

When developing a watermarking technique, one does not want to increasethe probability of a false alarm. That is when a watermark is detected,but none exists. This is something like finding evidence of a crime thatdid not happen. Someone may be falsely accused of wrongdoing.

As the probability of false alarms increases, the confidence in thewatermarking technique decreases. For example, people often ignore caralarms because they know that more often than not it is a false alarmrather than an actual car theft.

Likewise, one does not want to increase the probability of a miss. Thisis when the watermark of a signal is not properly detected. This issomething like overlooking key piece of evidence at a crime scene.Because of this, a wrongdoing may never be properly investigated. As theprobability of misses increases, the confidence in the watermarkingtechnique decreases.

Ideally, the probabilities of a false alarm and a miss are zero. Inreality, a compromise is often made between them. Typically, a decreasein the probability of one increases the probability of the other. Forexample, as the probability of false alarm is decreased, the probabilityof a miss increases.

Consequently, a watermarking technique is needed that minimizes bothwhile finding a proper balance between them.

Quantization Index Modulation (QIM)

To that end, some have proposed embedding a watermark by indexing thesignal (e.g., host data) during the watermark embedding. This techniqueis called quantization index modulation (QIM) and it was brieflyintroduced above.

In general, quantization means to limit the possible values of (amagnitude or quantity) to a discrete set of values. Quantization may bethought of as a conversion from non-discrete (e.g., analog orcontinuous) values to discrete values. Alternatively, it may be aconversion between discrete values with differing scales. Quantizationmay be accomplished mathematically through rounding or truncation.Typical QIM refers to embedding information by first modulating an indexor sequence of indices with the embedded information and then quantizingthe host signal with the associated quantizer or sequence of quantizers.A quantizer is class of discontinuous, approximate-identity functions.

The major proponent of such QIM techniques is Brian Chen and Gregory W.Wornell (i.e., Chen-Wornell). In their words, they have proposed,“dither modulation in which the embedded information modulates a dithersignal and the host signal is quantized with an associated ditherquantizer” (from Abstract of Chen-Wornell article from the IEEE Trans.Inform. Theory).

See the following documents for more details on Chen-Wornell's proposalsand on QIM:

-   B. Chen and G. W. Wornell, “Digital watermarking and information    embedding using dither modulation,” Proc. IEEE Workshop on    Multimedia Signal Processing, Redondo Beach, Calif., pp. 273-278,    December 1998;-   B. Chen and G. W. Wornell, “Dither modulation: a new approach to    digital watermarking and information embedding,” Proc. of SPIE:    Security and Watermarking of Multimedia Contents, vol. 3657, pp.    342-353, 1999;-   B. Chen and G. W. Wornell, “Quantization Index Modulation: A class    of Provably Good Methods for Digital Watermarking and Information    Embedding,” IEEE Trans. Inform. Theory, 1999 and 2000.    Limitations of Conventional QIM

However, a key problem with conventional QIM is that it is susceptibleto attacks and distortions. Conventional QIM relies upon localcharacteristics within relative to specific representation of a signal(e.g., in the time or frequency domain). To quantize, conventional QIMrelies exclusively upon the values of “individual coefficients” of therepresentation of the signal. An example of such an “individualcoefficients” is the color of an individual pixel of an image.

When quantizing, only the local characteristics of an “individualcoefficient” are considered. These local characteristics may includevalue (e.g., color, amplitude) and relative positioning (e.g.,positioning in time and/or frequency domains) of an individual bit(e.g., pixel).

Modifications—from either an attack or some type of unintentionalnoise—can change local characteristics of a signal quite dramatically.For example, these modifications may have a dramatic affect on the colorof a pixel or the amplitude of a bit of sound. However, suchmodifications have little effect on non-local characteristics of asignal.

Accordingly, a new and robust watermarking technique is needed to findthe proper balance between minimizing the probability of false alarmsand the probability of misses, such as QIM watermarking techniques.However, such a technique is needed that is less susceptible to attacksand distortions to the local characteristics within a signal.

SUMMARY

Described herein is a technology for deriving robust non-localcharacteristics and quantizing such characteristics for blindwatermarking of a digital good.

This summary itself is not intended to limit the scope of this patent.Moreover, the title of this patent is not intended to limit the scope ofthis patent. For a better understanding of the present invention, pleasesee the following detailed description and appending claims, taken inconjunction with the accompanying drawings. The scope of the presentinvention is pointed out in the appending claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The same numbers are used throughout the drawings to reference likeelements and features.

FIG. 1 is a schematic block diagram showing a watermarking architecturein accordance with an implementation of the invention claimed herein.

FIG. 2 is a schematic block diagram showing an embodiment (e.g., awatermark embedding system) of the invention claimed herein.

FIG. 3 is a flow diagram showing an illustrative methodologicalimplementation (e.g., watermark embedding) of the invention claimedherein.

FIG. 4 is a schematic block diagram showing an embodiment (e.g., awatermark detecting system) of the invention claimed herein.

FIG. 5 is a flow diagram showing an illustrative methodologicalimplementation (e.g., watermark detecting) of the invention claimedherein.

FIG. 6 is an example of a computing operating environment capable ofimplementing an implementation (wholly or partially) of the inventionclaimed herein.

DETAILED DESCRIPTION

In the following description, for purposes of explanation, specificnumbers, materials and configurations are set forth in order to providea thorough understanding of the present invention. However, it will beapparent to one skilled in the art that the present invention may bepracticed without the specific exemplary details. In other instances,well-known features are omitted or simplified to clarify the descriptionof the exemplary implementations of present invention, thereby betterexplain the present invention. Furthermore, for ease of understanding,certain method steps are delineated as separate steps; however, theseseparately delineated steps should not be construed as necessarily orderdependent in their performance.

The following description sets forth one or more exemplaryimplementations of a Derivation and Quantization of Robust Non-LocalCharacteristics for Blind Watermarking that incorporate elements recitedin the appended claims. These implementations are described withspecificity in order to meet statutory written description, enablement,and best-mode requirements. However, the description itself is notintended to limit the scope of this patent.

The inventors intend these exemplary implementations to be examples. Theinventors do not intend these exemplary implementations to limit thescope of the claimed present invention. Rather, the inventors havecontemplated that the claimed present invention might also be embodiedand implemented in other ways, in conjunction with other present orfuture technologies.

An example of an embodiment of a Derivation and Quantization of RobustNon-Local Characteristics for Blind Watermarking may be referred to as“exemplary non-local QIM watermarker.”

Incorporation by Reference

The following co-pending patent applications are incorporated byreference herein (which are all assigned to the Microsoft Corportaion):

-   U.S. patent application Ser. No. 09/390271, entitled “A Technique    for Watermarking an Image and a Resulting Watermarked Image” filed    Sep. 7, 1999;-   U.S. patent application Ser. No. 09/390272, entitled “A Technique    for Detecting a Watermark in a Marked Image” filed on Sep. 7, 1999;

U.S. patent application Ser. No. 09/614,660, entitled “Improved StealthyAudio Watermarking” filed on Jul. 12, 2000; and

-   U.S. patent application Ser. No. 09/316,899, entitled “Audio    Watermarking with Dual Watermarks” filed on May 22, 1999.    Introduction

The one or more exemplary implementations, described herein, of thepresent claimed invention may be implemented (in whole or in part) by anon-local QIM watermarking architecture 100 and/or by a computingenvironment like that shown in FIG. 6.

In general, the exemplary non-local QIM watermarker derives robustnon-local characteristics of a digital good. It quantizes suchcharacteristics for blind watermarking of the digital good.

The exemplary non-local QIM watermarker minimizes the probability offalse alarms (i.e., detecting a non-existent watermark) and theprobability of misses (i.e., failing to detect an existing watermark).It does so by employing quantization index modulation (QIM)watermarking. However, it does not employ conventional QIM techniquesbecause they are susceptible to attacks and distortions to the localcharacteristics of a digital good.

Local Characteristics

Conventional QIM relies upon local characteristics within a signal(i.e., a digital good). To quantize, conventional QIM relies exclusivelyupon the values of “individual elements” of the host signal. Whenquantizing, only the local characteristics of an “individual element”are considered. These local characteristics may include value (e.g.,color, amplitude) and relative positioning (e.g., positioning in timeand/or frequency domains) of an individual bit (e.g., pixel).

Modifications—from either an attack or unintentional noise—can changelocal characteristics of a signal quite dramatically. For example, thesemodifications may have a dramatic affect on the color of a pixel or theamplitude of a bit of sound. However, such modifications have littleeffect on non-local characteristics of a signal.

Non-Local Characteristics

Non-local characteristics are representative of general characteristicsof a group or collection of individual elements. Such a group may becalled a segment. Non-local characteristics are not representative ofthe individual local characteristics of the individual elements; rather,they are representative of the group (e.g., segments) as a whole.

The non-local characteristics may be determined by a mathematical orstatistical representation of a group. For example, it may be an averageof the color values of all pixels in a group. Consequently, suchnon-local characteristics may also be called “statisticalcharacteristics.” Local characteristics do not have statisticalcharacteristics because a fixed value for a given category. Thus, nostatistics are derived from a single value.

The non-local characteristics are not local characteristics. They arenot global characteristics. Rather, they are in between. Consequently,they may also be called “semi-global” characteristics.

Brief Overview

Given an original, unmarked good, the exemplary non-local QIMwatermarker derives robust characteristics that are not local in nature.For example, the exemplary non-local QIM watermarker may employrandomized non-invertible transforms to produce robust non-localcharacteristics that can be modified without perceptual distortion.These characteristics are typically represented statistically and/ormathematically.

To embed the watermark, the exemplary non-local QIM watermarker performsquantization of these non-local characteristics in one or moredimensional lattices or vector spaces. The marked good that results fromthe exemplary non-local QIM watermarker is robust against unintentionaland intentional modifications (e.g., malicious attacks). Examples ofmalicious attacks include de-synching, random bending, and many otherbenchmark attacks (e.g., Stirmark attacks).

Exemplary Non-Local QIM Watermarking Architecture

FIG. 1 shows a digital goods production and distribution architecture100 (i.e., non-local QIM watermarking architecture 100) having a contentproducer/provider 122 that produces original content and distributes thecontent over a network 124 to a client 126. The contentproducer/provider 122 has a content storage 130 to store digital goodscontaining original content. The content producer 122 has a watermarkembedding system 132 to sign the digital signals with a watermark thatuniquely identifies the content as original. The watermark embeddingsystem 132 may be implemented as a standalone process or incorporatedinto other applications or an operating system.

The watermark embedding system 132 applies the watermark to a digitalsignal from the content storage 130. Typically, the watermark identifiesthe content producer 122, providing a signature that is embedded in thesignal and cannot be cleanly removed.

The content producer/provider 122 has a distribution server 134 thatdistributes the watermarked content over the network 124 (e.g., theInternet). A signal with a watermark embedded therein represents to arecipient that the signal is being distributed in accordance with thecopyright authority of the content producer/provider 122. The server 134may further compress and/or encrypt the content conventional compressionand encryption techniques prior to distributing the content over thenetwork 124.

Typically, the client 126 is equipped with a processor 140, a memory142, and one or more content output devices 144 (e.g., display, soundcard, speakers, etc.). The processor 140 runs various tools to processthe marked signal, such as tools to decompress the signal, decrypt thedate, filter the content, and/or apply signal controls (tone, volume,etc.). The memory 142 stores an operating system 150 (such as aMicrosoft® Windows 2000® operating system), which executes on theprocessor. The client 126 may be embodied in many different ways,including a computer, a handheld entertainment device, a set-top box, atelevision, an appliance, and so forth.

The operating system 150 implements a client-side watermark detectingsystem 152 to detect watermarks in the digital signal and a contentloader 154 (e.g., multimedia player, audio player) to facilitate the useof content through the content output device(s) 144. If the watermark ispresent, the client can identify its copyright and other associatedinformation.

The operating system 150 and/or processor 140 may be configured toenforce certain rules imposed by the content producer/provider (orcopyright owner). For instance, the operating system and/or processormay be configured to reject fake or copied content that does not possessa valid watermark. In another example, the system could load unverifiedcontent with a reduced level of fidelity.

Exemplary Non-Local QIM Watermark Embedding System

FIG. 2 shows an exemplary non-local QIM watermark embedding system 1200,which is an example of an embodiment of a portion of the non-local QIMwatermarking architecture 100. This system may be employed as thewatermark encoding system 132 of FIG. 1.

The watermark embedding system 200 includes an amplitude normalizer 210,a transformer 220, a partitioner 230, segment-statistics calculator 240,a segment quantizer 250, a delta-sequence finder 260, and a signalmarker 270.

The amplitude normalizer 210 obtains a digital signal 205 (such as anaudio clip). It may obtain the signal from nearly any source, such as astorage device or over a network communications link. As its nameimplies, it normalizes the amplitude of the signal.

The transformer 220 receives the amplitude-normalized signal from thenormalizer 210. The transformer 220 puts the signal in canonical formusing a set of transformations. Specifically, discrete wavelettransformation (DWT) may be employed (particularly, when the input is animage) since it compactly captures significant signal characteristicsvia time and frequency localization. Other transformations may be used.For instance, shift-invariant and shape-preserving “complex wavelets”and any overcomplete wavelet representation or wavelet packet are goodcandidates (particularly for images).

The transformer 220 also finds the DC subband of the initialtransformation of the signal. This DC subband of the transformed signalis passed to the partitioner 230.

The partitioner 230 separates the transformed signal into multiple,pseudorandomly sized, pseudorandomly positioned, adjacent,non-contiguous segments (i.e., partitions). A secret key K is the seedfor pseudorandom number generation here. This same K may be used toreconstruct the segments by an exemplary non-local QIM watermarkdetecting system 400.

For example, if the signal is an image, it might be partitioned intotwo-dimensional polygons (e.g., rectangles) of pseudorandom size andlocation. In another example, if the signal is an audio clip, atwo-dimensional representation (using frequency and time) of the audioclip might be separated into two-dimensional polygons (e.g., triangles)of pseudorandom size and location.

In this implementation, the segments do not overlap. They are adjacentand non-contiguous. In alternative implementations, the segments may beoverlapping.

For each segment, the segment-statistics calculator 240 calculatesstatistics of the multiple segments generated by the partitioner 230.Statistics for each segment are calculated. These statistics may be, forexample, any finite order moments of a segment. Examples of such includethe mean, the median, and the standard deviation.

Generally, the statistics calculations for each segment are independentof the calculations of other segments. However, other alternatives mayinvolve calculations dependent on data from multiple segments.

A suitable statistic for such calculation is the mean (e.g., average) ofthe values of the individual bits of the segment. Other suitablestatistics and their robustness are discussed in Venkatesan, Koon,Jakubowski, and Moulin, “Robust image hashing,” Proc. IEEE ICIP 2000,Vancouver, Canada, September 2000. In this document, no informationembedding was considered, but similar statistics were discussed.

For each segment, the segment quantizer 250 applies a multi-level (e.g.,2, 3, 4) quantization (i.e., high-dimensional, vector-dimensional, orlattice-dimensional quantization) on the output of thesegment-statistics calculator 240 to obtain quantitized data. Of course,other levels of quantization may be employed. The quantizer 250 may beadaptive or non-adaptive.

This quantization may be done randomly also. This may be calledrandomized quantization (or randomized rounding). This means that thequantizer may randomly decide to round up or round down. It may do itpseudorandomly (using the secret key). This adds an additional degree ofrobustness and helps hide the watermark.

The delta-sequence finder 260 finds a pseudorandom sequence Z thatestimates the difference (i.e., delta) between the original transformedsignal X and the combination of segments of quantized statistics. Thepseudorandom sequence Z may also be called the delta-sequence. Forexample, if the statistic is averaging, then Z s.t.Avg_(i)(X+Z)=Avg_(i)({circumflex over (X)})={circumflex over (μ)}_(i),where {circumflex over (X)} is the marked signal and {circumflex over(μ)}_(i) is average for a segment.

When finding a delta-sequence Z, it is desirable to minimize theperceptual distortion; therefore, some perceptual distortion metrics maybe employed to create this sequence. Thus, in creating Z for, thecriteria may include a combination of that minimizes the visualdistortions on X+Z (compared to {circumflex over (X)}) and minimizes thedistance between the statistics of X+Z and quantized statistics of X.

The signal marker 270 marks the signal with delta-sequence Z so that{circumflex over (X)}=X+Z . The signal marker may mark the signal usingQIM techniques. This marked signal may be publicly distributed toconsumers and clients.

The functions of aforementioned components of the exemplary non-localQIM watermark embedding system 200 of FIG. 2 are explained in moredetail below.

Methodological Implementation of the Exemplary Non-Local QIM WatermarkEmbedding

FIG. 3 shows the methodological implementation of the exemplarynon-local QIM watermark embedding system 200 (or some portion thereof).More specifically, this figure shows the methodological implementationof watermark embedding of the exemplary non-local QIM watermarker. Thismethodological implementation may be performed in software, hardware, ora combination thereof.

At 310 of FIG. 3, the exemplary non-local QIM watermarker normalizes theamplitude of the input. The input is the original, unmarked signal(i.e., digital good). At 312, it finds a transform of theamplitude-normalized signal and gets the lowest frequency band (e.g.,the DC subband). The result of this block is a transformed signal. Thistransformation is a discrete wavelet transformation (DWT), but most anyother similar transformation may be performed in alternativeimplementations.

At 314, the exemplary non-local QIM watermarker partitions thetransformed signal into multiple, pseudorandomly sized, pseudorandomlypositioned, adjacent, non-contiguous segments. A secret key K is theseed for pseudorandom number generation here. This same K may be used toreconstruct the segments in the watermark detecting process.

For example, if the signal is an image, it might be separated intotwo-dimensional polygons (e.g., rectangles) of pseudorandom size andlocation. In another example, if the signal is an audio clip, atwo-dimensional representation (using frequency and time) of the audioclip might be separated into two-dimensional polygons (e.g., trapezoids)of pseudorandom size and location.

In this implementation, the segments do not overlap. They are adjacentand non-contiguous. In alternative implementations, the segments may beoverlapping.

For each segment of the signal, the exemplary non-local QIM watermarkerrepeats blocks 320 through 330. Thus, each segment is processed in thesame manner.

At 322 of FIG. 3, the exemplary non-local QIM watermarker has awatermark (or a portion thereof) to embed in the current segment. Itfinds quantized values of statistics of the segment (e.g., averageswithin the segment or as close as possible). At this point, scalaruniform quantizer and reconstruction points may be randomly perturbedwith K as the seed.

At 324, the exemplary non-local QIM watermarker finds a pseudorandomsequence Z where the statistics calculation (e.g., averaging) of thissequence combined with the segmented signal generates the calculation ofwatermarked signal segment. This is also equal to the quanitizedstatistics of the signal segment.

At 330, the process loops back to 320 for each unprocessed segment. Ifall segments have been processed, then it proceeds to 340.

At 340 of FIG. 3, the exemplary non-local QIM watermarker combines thepseudorandom sequence with the signal segments to get the watermarkedsignal segments. In addition, the watermarked signal segments arecombined to form a full watermarked signal. In other words, {circumflexover (X)}=X+Z. At 350, the process ends.

Exemplary Non-Local QIM Watermark Detecting System

FIG. 4 shows an exemplary non-local QIM watermark detecting system 400,which is an example of an embodiment of a portion of the non-local QIMwatermarking architecture 100. This system may be employed as thewatermark detecting system 152 of FIG. 1.

The watermark detecting system 400 includes an amplitude normalizer 410,a transformer 420, a partitioner 430, segment-statistics calculator 440,a segment MAP decoder 450, a watermark-presence determiner 460, apresenter 470, and a display 480.

The amplitude normalizer 410, the transformer 420, the partitioner 430,and the segment-statistics calculator 440 of the watermark detectingsystem 400 of FIG. 4 function in a similar manner as similarly labeledcomponents of the watermark embedding system 200 of FIG. 2. Theexception is that the object of these components is a “subject signal”rather than the original signal. A “subject signal” signal is anunknown. It may or may not include a watermark. It may have beenmodified.

For each segment, the segment MAP decoder 450 determines a quantizedvalue using the MAP decoding scheme. In general, MAP techniques involvefinding (and possibly ranking by distance) all objects (in thisinstance, quantized values) in terms of their distance from a “point.”In this example, the “point” is the statistics calculated for a givensegment. Nearest-neighbor decoding is one specific instance of MAPdecoding. Those of ordinary skill in the art understand and appreciateMAP and nearest-neighbor techniques.

In addition, the segment MAP decoder 450 determines a confidence factorbased upon the distance between the quanitized values and the statisticscalculated for a given segment. If they are coexistent, then factor willindicate a high degree of confidence. If they are distant, then it mayindicate a low degree of confidence. Furthermore, the decoder 450combines the confidence factors of the segments to get an overallconfidence factor. That combination may be most any statisticalcombination (e.g., addition, average, median, standard deviation, etc.).

The watermark-presence determiner 460 determines whether a watermark ispresent. The determiner may use some distortion metric d(w,ŵ) and somethreshold T to decide if watermark is present or not. A normalizedHamming distance may be used.

The presenter 470 presents one of three indications: “watermarkpresent,” “watermark not present,” and “unknown.” If the confidencefactor is low, it may indicate “unknown.” In addition, it may presentthe confidence-indication value.

This information is presented on the display 480. Of course, thisdisplay may be any output device. It may also be a storage device.

The functions of aforementioned components of the exemplary non-localQIM watermark detecting system 400 of FIG. 4 are explained in moredetail below.

Methodological Implementation of the Exemplary Non-Local QIM WatermarkDetecting

FIG. 5 shows the methodological implementation of the exemplarynon-local QIM watermark detecting system 400 (or some portion thereof).More specifically, this figure shows the methodological implementationof watermark detecting of the exemplary non-local QIM watermarker. Thismethodological implementation may be performed in software, hardware, ora combination thereof.

At 510 of FIG. 5, the exemplary non-local QIM watermarker normalizes theamplitude of the input. The input is an unknown specimen (i.e., signal)of a digital good. It is not known whether this signal includes awatermark or not.

At 512, it finds a transform of the amplitude-normalized signal and getssignificant frequency subband. That may be a low or the lowest subband(e.g., the DC subband). Generally, the subband selected may be one thatrepresents the signal is a manner that helps further robust watermarkingand detection of the watermark. The lower frequency subbands aresuitable because they tend to remain relatively invariant after signalperturbation.

The result of this block is a transformed signal. When watermarking animage, an example of a suitable transformation is discrete wavelettransformation (DWT). When watermarking an audio clip, an example of asuitable transformation is MCLT (Modulated Complex Lapped Transform).However, most any other similar transformation may be performed inalternative implementations.

At 514, the exemplary non-local QIM watermarker partitions thetransformed signal into multiple, pseudorandomly sized, pseudorandomlypositioned, adjacent, non-contiguous segments. It uses the same secretkey K is the seed for its pseudorandom number generation here.Therefore, this process generates the same segments as in the embeddingprocess.

For each segment of the signal, the exemplary non-local QIM watermarkerrepeats blocks 520 through 530. Thus, each segment is processed in thesame manner.

At 522 of FIG. 5, the exemplary non-local QIM watermarker findsstatistics of the segment (e.g., averages within the segment). At 524,the exemplary non-local QIM watermarker finds decoded watermark (or aportion thereof) using Maximum A Posteriori (MAP) decoding. An exampleof such a MAP decoding is nearest-neighbor decoding.

At 526, it measures how close each decoded value is to a quanitizedvalue and tracks such measurements. The data provided by suchmeasurements may provide an indication of the confidence of a resultingwatermark-presence determination.

At 530, the process loops back to 520 for each unprocessed segment. Ifall segments have been processed, then it proceeds to 540.

At 540 of FIG. 5, the exemplary non-local QIM watermarker determineswhether a watermark is present. At 542, it determines aconfidence-indication, which is based upon the tracked measurement data.

At 544, based upon the watermark-presence determination of block 540 andthe confidence-indication of block 544, the exemplary non-local QIMwatermarker provides one of three indications: watermark present,watermark not present, and unknown. In addition, it may present theconfidence-indication value.

At 550, the process ends.

Probability of False Alarms and Misses

There is a relationship between Probability of false alarm (P_(F)),Probability of miss (P_(M)), and the average sizes of the segments.P_(F) is the probability of declaring that a watermark is present eventhough it is not. P_(M) is the probability declaring that a watermark isnot present although it is present indeed. Generally, the averagesegment size is relatively directly proportional to the P_(F), but it isrelatively indirectly proportional to the P_(M).

For example, if the average segment-size is extremely small. So smallthat they are equivalent to the individual bits (e.g., equal to a pixelin an image. In that situation, watermarks are embedded in singlecoefficients, which is equivalent to the conventional schemes based onlocal characteristics. For such a case, P_(F) is very small and P_(M) ishigh. Conversely, if the average segment-size is extremely large. Solarge that it is the maximum size of the signal (e.g., the whole image).In that situation, P_(M) is presumably very low whereas P_(F) is high.

Other Implementation Details

For the following descriptions of an implementation of the exemplarynon-local QIM watermarker, assume the following:

The input signal X is an image. Of course, for signal may be other typesfor other implementations. However, for this example implementation, thesignal is an image. Let w be the watermark (a binary vector) to beembedded in X and a random binary string K be the secret key. The outputof a watermark encoder, {circumflex over (X)} is the watermarked imagein which the information w is hidden via the secret key K. This imagewill possibly undergo various attacks, yielding {circumflex over (X)}. Awatermark decoder, given {circumflex over (X)} and the secret key Koutputs ^(ŵ) . It is required that {circumflex over (X)} and ^(X) areapproximately the same for all practical purposes and that {circumflexover (X)} is still of acceptable quality. The decoder uses somedistortion metric d(w, ŵ) and some threshold T to decide if watermark ispresent or not. The exemplary non-local QIM watermarker use a normalizedHamming distance, which is the ratio of the usual Hamming distance andthe length of the inputs.

WM via Quantization

The exemplary non-local QIM watermarker computes a vector μ by applyinga forward transformation T_(F) on X. The exemplary non-local QIMwatermarker assumes that X is a grayscale image; if not, a lineartransformation may be applied on a colored image to obtain the intensityimage. (For colored images, most of the energy is concentrated in theintensity plane). Once the information hiding process is done viaquantization, there is ^({circumflex over (μ)}) , and the watermarkeddata {circumflex over (X)} are obtained by applying the transform T_(R)on {circumflex over (μ)}. The exemplary non-local QIM watermarkerrandomizes the process using a random string derived from our secret keyK as a seed to a pseudo-random generator.

The scheme is generic. So most any transform may be used. In addition,T_(F)=(T_(R))⁻¹ need not be true, or even that their inverses exist. Theexemplary non-local QIM watermarker does not constrain the space wherequantization occurs. The decoder applys the transform T_(F) on theinput, Y, to get the output is μ _(Y) and applying approximate MaximumLikelihood (ML) estimation of the possibly embedded sequence ŵ _(Y).Through a pseudo-random generator, K will determine many randomizationfunctions of the transform, quantization and estimation stages. Once ŵ_(Y) is found, it is compared with the embedded watermark w, if thedistance between them is close to 0 (or less than a threshold T), thenit is declared that the watermark is present; otherwise not present.This contrasts with the natural measure for spread spectrum techniquesthat yields a high value of correlation if the watermark is present.

More Details of this Methodological Implementation

The transforms T_(F) and T_(R) help enhance robustness. For T_(F) toretain significant image characteristics, we may use discrete wavelettransformation (DWT) at the initial stage. Next, semi-global (i.e.,non-local) statistics of segments are determined of the image. The localstatistics are not robust.

When the exemplary non-local QIM watermarker computes, for example, thefirst order statistics of an original image signal and computes severalattacked versions for random rectangles of fixed size. Then the averagemean squared error between these statistics may be found. The errormonotonically decays as the size of the rectangles is increased.

In T_(F), μ is set to be the estimated first order statistics ofrandomly chosen rectangles in the wavelet domain. Here T_(F) is notinvertible if the number of rectangles is less than the number ofcoefficients. To choose T_(R), one might first generate a pseudo-randomsequence p in the image domain that has the property to be visuallyapproximately unnoticeable, pass it through T_(F), find thecorresponding statistics μ _(p), compute the necessary scaling factors αsuch that the pseudorandom sequence p scaled by α and added to X yieldsthe averages {circumflex over (μ)} that is quantized μ. Thisimplementation uses randomly chosen non-overlapping rectangles. Theexemplary non-local QIM watermarker defines two quantizers, Q₀ and Q₁,which map vectors in

^(n) to some nearby chosen lattice points.

Here is a formal description. Define Q_(i):={(q_(ij),

_(ij))|j∈

}; q_(ij)∈

^(n) to be reconstruction points for Q_(i);

_(ij)⊂ are the corresponding quantization bins; i∈{0,1}, j∈

. For each j, then

_(0j)∩[(∪_(k≠j)

_(0k))∪(∪_(k)

_(1k))]=

_(ij)∩[(∪_(k≠j)

_(1k))∪(∪_(k)

_(0k))]=Ø. Here q_(0j),q_(1j) are determined in a pseudo-random fashion(using K as the seed of the random number generator) and n is thedimension of quantization. The exemplary non-local QIM watermarkerdefines Q₀[α]=q_(0j)

α∈

_(0j), and likewise for Q₁. Both Q₀ and Q₁ are derived from a singlequantizer, Q, such that (a) the set of reconstruction points of Q isequal to {q_(0j)}_(j)∪{q_(1j)}_(j) and (b) for all j,k,min_(l∈Z)d_(L2)[E(q_(0j)), E(q_(1l))]=min_(l∈Z)d_(L2)[E(q_(0l)),E(q_(1k))]. Let ζ denote the common value (c) for each fixed k,φ_(k):=min_(j≠k)d_(L2)[E(q_(0j)), E(q_(0k))]=min_(j≠k)d_(L2)[E(q_(1j)),E(q_(1j)), E(q_(1k))] and φ_(i)=φ_(j)>ζ for all i,j. Here d_(L2) is theL₂ distortion metric, and E(.) is the expectation operator over thepseudo-random choices q_(ij).

If, for example, n=1. The exemplary non-local QIM watermarker finds{E(q_(0j))} and {E(q_(ij))} meeting the requirements mentioned above.Then randomization regions that are neighborhoods in

^(n) around {E(q_(0j))} and {E(q_(1j))} are introduced. Then {q_(0j)}and {q_(1j)} are randomly choosen from these regions using some suitableprobability distributions. The sizes of the randomizing regions andtheir shapes are input parameters. Let nR be the number of rectangleseach indexed suitably. Let R be the length of the binary watermarkvector w to be hidden in rectangles. For a vector, v denotes its i-thentry by v(i). Let L denote the number of levels of DWT that is applied.

Encoding

Let N be the number of pixels in X and s:=[s₁, . . . , s_(N)] be thevector that consists of pixels of X sorted in ascending order. Createsubvectors s _(L):=[s_(t), . . . , s_(t′)] where t:=round(N(1−β)γ) andt′=round(N(1+β)γ) and s _(H):=[s_(u), s_(u′)] where u=round(N[1−(1−β)γ])and u′=round(N[(1+β)γ]). Here round(r) equals the nearest integer to rand the system parameters 0<β,γ<<1. Let m and M be the mean values ofthe elements of s _(L) of s _(H) respectively. Apply the point operatorP[χ]=255*(χ−m)/(M−m) to each element of X to get X′.

Find the L-level DWT of X ^(j) . Let X _(A) be its DC subband.

Partition the X _(A) into random non overlapping nR rectangles;calculate μ such that μ(i) is the mean value of the coefficients withinrectangle i, i≦nR.

Let μ ^(i):=[μ(n(i−1)+1), . . . , μ(ni−1), μ(ni)], i≦R. Use Q₀ and Q₁ toquantize: for i≦R, if w(i)=0, quantize μ ^(i) using Q₀ else quantize μ^(i) using Q₁. Concatenating the quantized {μ ^(i)} we get {circumflexover (μ)}.

Find the differences between the original statistics and the quantizedstatistics: d={circumflex over (μ)}−μ.

Generate a pseudo-random sequence p=[p_(ij) ^(])in the spatial (i.e. theoriginal image) domain as follows: Choose p_(ij) randomly and uniformlyfrom {0,1} if s_(t′)<X_(ij)<s_(t), where t′=round(Nγ) andt=round(N(1−γ)); otherwise set p_(ij)=0. Now apply L-level DWT to thematrix p, extract the DC subband of the output and call it p _(W). Nowcompute the corresponding statistics similar to the step

Compute the scaling factors α such that α(i)=d(i)/μ _(p)(i), i≦nR.

For each rectangle whose index is i, multiply all coefficients of ^(p)_(W) within that rectangle by α(i), let the resulting vector be{circumflex over (p)} _(W).

Apply inverse DWT on {circumflex over (p)} _(W), let the output be{circumflex over (p)}.

Compute the watermarked data: X″=X′+{circumflex over (p)}. Apply theinverse of the point operator (see step 1) on X″ to get {circumflex over(X)}.

Decoding (input Y):

Similar to first part of the encoding above, find the correspondingpoint operator on Y. Now apply the operator to Y and to the output applyL-level DWT, extract the DC subband and call it Y _(A).

Applying the partitioning procedure of the encoding above to Y and findits statistics μ _(Y). Let μ _(Y)(i) be the ith element.

Using Q₀ and Q₁, now is described how to carry out approximate MLestimation to find the decoded sequence w _(Y: Let μ) _(Y) ^(i):=[μ_(Y)(n(i−1)+1), . . . , μ _(Y)(ni−1), μ _(Y)(ni)]. For rectanglesindexed by n(i−1)+1, . . . , ni−1, ni, i≦R, let r0(i) be the closestpoint to μ _(Y) ^(i) among reconstruction points of Q₀; likewise letr1(i) be the closest point to μ _(Y) ^(i) among reconstruction points ofQ₁. If d_(l2)(μ _(Y) ^(i), r0(i)<d_(l2)(μ _(Y) ^(i) ^(, r)1(i)) thenassign w _(Y)(i)=0; otherwise w _(Y)(i)=1.

Compute d(w _(Y),w). If the result is less than threshold T, declarethat the watermark was detected, or otherwise not present.

Exemplary Computing System and Environment

FIG. 6 illustrates an example of a suitable computing environment 900within which an exemplary non-local QIM watermarker, as describedherein, may be implemented (either fully or partially). The computingenvironment 900 may be utilized in the computer and networkarchitectures described herein.

The exemplary computing environment 900 is only one example of acomputing environment and is not intended to suggest any limitation asto the scope of use or functionality of the computer and networkarchitectures. Neither should the computing environment 900 beinterpreted as having any dependency or requirement relating to any oneor combination of components illustrated in the exemplary computingenvironment 900.

The exemplary non-local QIM watermarker may be implemented with numerousother general purpose or special purpose computing system environmentsor configurations. Examples of well known computing systems,environments, and/or configurations that may be suitable for useinclude, but are not limited to, personal computers, server computers,thin clients, thick clients, hand-held or laptop devices, multiprocessorsystems, microprocessor-based systems, set top boxes, programmableconsumer electronics, network PCs, minicomputers, mainframe computers,distributed computing environments that include any of the above systemsor devices, and the like.

The exemplary non-local QIM watermarker may be described in the generalcontext of computer-executable instructions, such as program modules,being executed by a computer. Generally, program modules includeroutines, programs, objects, components, data structures, etc. thatperform particular tasks or implement particular abstract data types.The exemplary non-local QIM watermarker may also be practiced indistributed computing environments where tasks are performed by remoteprocessing devices that are linked through a communications network. Ina distributed computing environment, program modules may be located inboth local and remote computer storage media including memory storagedevices.

The computing environment 900 includes a general-purpose computingdevice in the form of a computer 902. The components of computer 902 caninclude, by are not limited to, one or more processors or processingunits 904, a system memory 906, and a system bus 908 that couplesvarious system components including the processor 904 to the systemmemory 906.

The system bus 908 represents one or more of any of several types of busstructures, including a memory bus or memory controller, a peripheralbus, an accelerated graphics port, and a processor or local bus usingany of a variety of bus architectures. By way of example, sucharchitectures can include an Industry Standard Architecture (ISA) bus, aMicro Channel Architecture (MCA) bus, an Enhanced ISA (EISA) bus, aVideo Electronics Standards Association (VESA) local bus, and aPeripheral Component Interconnects (PCI) bus also known as a Mezzaninebus.

Computer 902 typically includes a variety of computer readable media.Such media can be any available media that is accessible by computer 902and includes both volatile and non-volatile media, removable andnon-removable media.

The system memory 906 includes computer readable media in the form ofvolatile memory, such as random access memory (RAM) 910, and/ornon-volatile memory, such as read only memory (ROM) 912. A basicinput/output system (BIOS) 914, containing the basic routines that helpto transfer information between elements within computer 902, such asduring start-up, is stored in ROM 912. RAM 910 typically contains dataand/or program modules that are immediately accessible to and/orpresently operated on by the processing unit 904.

Computer 902 may also include other removable/non-removable,volatile/non-volatile computer storage media. By way of example, FIG. 6illustrates a hard disk drive 916 for reading from and writing to anon-removable, non-volatile magnetic media (not shown), a magnetic diskdrive 918 for reading from and writing to a removable, non-volatilemagnetic disk 920 (e.g., a “floppy disk”), and an optical disk drive 922for reading from and/or writing to a removable, non-volatile opticaldisk 924 such as a CD-ROM, DVD-ROM, or other optical media. The harddisk drive 916, magnetic disk drive 918, and optical disk drive 922 areeach connected to the system bus 908 by one or more data mediainterfaces 925. Alternatively, the hard disk drive 916, magnetic diskdrive 918, and optical disk drive 922 can be connected to the system bus908 by one or more interfaces (not shown).

The disk drives and their associated computer-readable media providenon-volatile storage of computer readable instructions, data structures,program modules, and other data for computer 902. Although the exampleillustrates a hard disk 916, a removable magnetic disk 920, and aremovable optical disk 924, it is to be appreciated that other types ofcomputer readable media which can store data that is accessible by acomputer, such as magnetic cassettes or other magnetic storage devices,flash memory cards, CD-ROM, digital versatile disks (DVD) or otheroptical storage, random access memories (RAM), read only memories (ROM),electrically erasable programmable read-only memory (EEPROM), and thelike, can also be utilized to implement the exemplary computing systemand environment.

Any number of program modules can be stored on the hard disk 916,magnetic disk 920, optical disk 924, ROM 912, and/or RAM 910, includingby way of example, an operating system 926, one or more applicationprograms 928, other program modules 930, and program data 932. Each ofsuch operating system 926, one or more application programs 928, otherprogram modules 930, and program data 932 (or some combination thereof)may include an embodiment of an amplitude normalizer, a transformer, apartitioner, a segment-statistics calculator, a segment quantizer, andelta-sequence finder, and a signal marker.

A user can enter commands and information into computer 902 via inputdevices such as a keyboard 934 and a pointing device 936 (e.g., a“mouse”). Other input devices 938 (not shown specifically) may include amicrophone, joystick, game pad, satellite dish, serial port, scanner,and/or the like. These and other input devices are connected to theprocessing unit 904 via input/output interfaces 940 that are coupled tothe system bus 908, but may be connected by other interface and busstructures, such as a parallel port, game port, or a universal serialbus (USB).

A monitor 942 or other type of display device can also be connected tothe system bus 908 via an interface, such as a video adapter 944. Inaddition to the monitor 942, other output peripheral devices can includecomponents such as speakers (not shown) and a printer 946 which can beconnected to computer 902 via the input/output interfaces 940.

Computer 902 can operate in a networked environment using logicalconnections to one or more remote computers, such as a remote computingdevice 948. By way of example, the remote computing device 948 can be apersonal computer, portable computer, a server, a router, a networkcomputer, a peer device or other common network node, and the like. Theremote computing device 948 is illustrated as a portable computer thatcan include many or all of the elements and features described hereinrelative to computer 902.

Logical connections between computer 902 and the remote computer 948 aredepicted as a local area network (LAN) 950 and a general wide areanetwork (WAN) 952. Such networking environments are commonplace inoffices, enterprise-wide computer networks, intranets, and the Internet.

When implemented in a LAN networking environment, the computer 902 isconnected to a local network 950 via a network interface or adapter 954.When implemented in a WAN networking environment, the computer 902typically includes a modem 956 or other means for establishingcommunications over the wide network 952. The modem 956, which can beinternal or external to computer 902, can be connected to the system bus908 via the input/output interfaces 940 or other appropriate mechanisms.It is to be appreciated that the illustrated network connections areexemplary and that other means of establishing communication link(s)between the computers 902 and 948 can be employed.

In a networked environment, such as that illustrated with computingenvironment 900, program modules depicted relative to the computer 902,or portions thereof, may be stored in a remote memory storage device. Byway of example, remote application programs 958 reside on a memorydevice of remote computer 948. For purposes of illustration, applicationprograms and other executable program components such as the operatingsystem are illustrated herein as discrete blocks, although it isrecognized that such programs and components reside at various times indifferent storage components of the computing device 902, and areexecuted by the data processor(s) of the computer.

Computer-Executable Instructions

An implementation of an exemplary non-local QIM watermarker may bedescribed in the general context of computer-executable instructions,such as program modules, executed by one or more computers or otherdevices. Generally, program modules include routines, programs, objects,components, data structures, etc. that perform particular tasks orimplement particular abstract data types. Typically, the functionalityof the program modules may be combined or distributed as desired invarious embodiments.

Exemplary Operating Environment

FIG. 6 illustrates an example of a suitable operating environment 900 inwhich an exemplary non-local QIM watermarker may be implemented.Specifically, the exemplary non-local QIM watermarker(s) describedherein may be implemented (wholly or in part) by any program modules928-930 and/or operating system 926 in FIG. 6 or a portion thereof.

The operating environment is only an example of a suitable operatingenvironment and is not intended to suggest any limitation as to thescope or use of functionality of the exemplary non-local QIMwatermarker(s) described herein. Other well known computing systems,environments, and/or configurations that are suitable for use include,but are not limited to, personal computers (PCs), server computers,hand-held or laptop devices, multiprocessor systems,microprocessor-based systems, programmable consumer electronics,wireless phones and equipments, general- and special-purpose appliances,application-specific integrated circuits (ASICs), network PCs,minicomputers, mainframe computers, distributed computing environmentsthat include any of the above systems or devices, and the like.

Computer Readable Media

An implementation of an exemplary non-local QIM watermarker may bestored on or transmitted across some form of computer readable media.Computer readable media can be any available media that can be accessedby a computer. By way of example, and not limitation, computer readablemedia may comprise “computer storage media” and “communications media.”

“Computer storage media” include volatile and non-volatile, removableand non-removable media implemented in any method or technology forstorage of information such as computer readable instructions, datastructures, program modules, or other data. Computer storage mediaincludes, but is not limited to, RAM, ROM, EEPROM, flash memory or othermemory technology, CD-ROM, digital versatile disks (DVD) or otheroptical storage, magnetic cassettes, magnetic tape, magnetic diskstorage or other magnetic storage devices, or any other medium which canbe used to store the desired information and which can be accessed by acomputer.

“Communication media” typically embodies computer readable instructions,data structures, program modules, or other data in a modulated datasignal, such as carrier wave or other transport mechanism. Communicationmedia also includes any information delivery media.

The term “modulated data signal” means a signal that has one or more ofits characteristics set or changed in such a manner as to encodeinformation in the signal. By way of example, and not limitation,communication media includes wired media such as a wired network ordirect-wired connection, and wireless media such as acoustic, RF,infrared, and other wireless media. Combinations of any of the above arealso included within the scope of computer readable media.

Conclusion

Although the invention has been described in language specific tostructural features and/or methodological steps, it is to be understoodthat the invention defined in the appended claims is not necessarilylimited to the specific features or steps described. Rather, thespecific features and steps are disclosed as preferred forms ofimplementing the claimed invention.

1. A computer implemented method for facilitating the protection ofdigital signals, the method comprising obtaining a digital signal;partitioning the signal into a plurality of segments using a secret key;obtaining a watermark; and using quantization index modulation (QIM),watermarking the signal with the watermark, wherein such QIM is basedupon non-local characteristics of the plurality of segments.
 2. A methodas recited in claim 1, wherein the non-local characteristics arerepresentative characteristics of more than a single element of asignal.
 3. A method as recited in claim 1, wherein: the QIM is performedon statistics calculated for each said segment; and the statistics forat least one said segment are based upon non-local characteristics of atleast one other segment.
 4. A method as recited in claim 1 wherein theplurality of segments are pseudorandomly positioned.
 5. A method asrecited in claim 1 wherein the plurality of segments are pseudorandomlypositioned using the secret key, such that said segments are adjacentand non-contiguous.
 6. A method as recited in claim 1, wherein thedigital signal is selected from a group consisting of a digital audiosignal, a digital video signal, a digital image signal, a digitalmultimedia signal, and a digital music signal.
 7. A modulated signalembodied on one or more tangible computer-readable media and generatedin accordance with the acts recited in claim
 1. 8. One or morecomputer-readable media having computer-executable instructions that,when executed by a computer, perform the acts recited in claim
 1. 9. Oneor more computer-readable media having computer-executable instructionsthat, when executed by a computer, perform the acts comprising:obtaining a digital signal; partitioning the signal into a plurality ofsegments using a secret key; obtaining a watermark; and usingquantization index modulation (QIM), watermarking the signal with thewatermark, wherein such QIM is based upon non-local characteristics ofthe plurality of segments.
 10. One or more media as recited in claim 9,wherein the non-local characteristics are representative characteristicsof more than a single element of a signal.
 11. One or more media asrecited in claim 9, wherein: the QIM uses statistics generated for eachsaid segment; and the statistics for each said segment are based in partupon non-local characteristics of at least two said segments.
 12. One ormore media as recited in claim 9 wherein the plurality of segments arepseudorandomly positioned.
 13. One or more media as recited in claim 9wherein the plurality of segments are positioned using the secret key,such that said segments are adjacent and non-contiguous.
 14. A computerimplemented method for facilitating the protection of digital signals,the method comprising obtaining a digital signal; partitioning thesignal into a plurality of segments; and quantizing statisticsassociated with each said segment to watermark the signal, wherein thestatistics associated with at least one said segment are determinedusing the non-local characteristics of at least two said segments.
 15. Amethod as recited in claim 14, wherein the quantizing includesquantization index modulation (QIM).
 16. A method as recited in claim14, wherein the plurality of segments are generated using a secret key.17. A method as recited in claim 14, wherein the plurality of segmentsare pseudorandomly positioned.
 18. A method as recited in claim 14,wherein the plurality of segments are positioned using the secret key,such that they are adjacent and non-contiguous.